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Double NAT help needed

eaglesfan73
Level 1
Level 1

 

 

 

Hello

I am trying the setup a Cisco 2801 router behind my Comcast router. I do not want to put the Comcast device in bridge mode, I want to use the wireless from it. I am not sure what I am doing wrong. This setup worked fine when I was using an old Linksys router in place of the 2801 router.

interface FastEthernet0/0

description UPLINK TO COMCAST ROUTER

ip address dhcp

ip nat outside

ip virtual-reassembly

speed auto

full-duplex

!

interface FastEthernet0/1

description LAN SEGMENT

ip address 192.168.1.1 255.255.255.0

ip nat inside

ip virtual-reassembly

speed auto

full-duplex

!

interface Serial0/1/0

no ip address

shutdown

!

interface Serial0/2/0

no ip address

shutdown

!

ip default-gateway 192.168.1.1

ip forward-protocol nd

!

!

ip http server

no ip http secure-server

ip nat source list 50 interface FastEthernet0/0 overload

ip nat inside source static tcp 192.168.1.150 80 interface FastEthernet0/0 80

!

access-list 50 permit 192.168.1.0 0.0.0.255

 

!

RTR_2801#ping 8.8.8.8

Type escape sequence to abort.

Sending 5, 100-byte ICMP Echos to 8.8.8.8, timeout is 2 seconds:

!!!!!

Success rate is 100 percent (5/5), round-trip min/avg/max = 12/12/16 ms

RTR_2801#ping 10.0.0.1

Type escape sequence to abort.

Sending 5, 100-byte ICMP Echos to 10.0.0.1, timeout is 2 seconds:

!!!!!

 

Success rate is 100 percent (5/5), round-trip min/avg/max = 1/2/4 ms

RTR_2801#ping 192.168.1.111

Type escape sequence to abort.

Sending 5, 100-byte ICMP Echos to 192.168.1.111, timeout is 2 seconds:

 

!!!!!

PC info

IP Addresss           192.168.1.111

Subnet Address     255.255.255.0

Default Gateway   192.168.1.1

DNS                      192.168.1.1

DNS                      75.75.75.75

 

This is for a lab environment, so when I mess up the wireless still works in the rest of the house. I have a webserver at 192.168.1.150 that worked without any issue using the old Linksys and double NAT

 

 

Thanks in advance

1 Accepted Solution

Accepted Solutions

pi_networks
Level 1
Level 1

Change "ip default-gateway 192.168.1.1"

to "ip default-gateway 10.0.0.1" (point towards your Comcast router ... guessing 10.0.0.1)

 

Change "ip nat source list 50 interface FastEthernet0/0 overload"

to "ip nat inside source list 50 interface FastEthernet0/0 overload"

 

Make sure that "ip routing" is enabled (your post doesn't include that config section)

 

See if that helps.

View solution in original post

2 Replies 2

pi_networks
Level 1
Level 1

Change "ip default-gateway 192.168.1.1"

to "ip default-gateway 10.0.0.1" (point towards your Comcast router ... guessing 10.0.0.1)

 

Change "ip nat source list 50 interface FastEthernet0/0 overload"

to "ip nat inside source list 50 interface FastEthernet0/0 overload"

 

Make sure that "ip routing" is enabled (your post doesn't include that config section)

 

See if that helps.

Thank you for your response, I will try it tonight and let you know.

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